Much attention has been given in recent years to the danger of transmitting diseases by being pricked by used syringe needles. Many patents have issued on syringes having disposable protected needles, e.g., U.S. Pat. Nos. 4,927,414; 4,941,883; and 4,943,282.
There also have been some developments in providing a syringe which receives a capsule of the injection fluid, rather than to resort to puncturing the diaphragm of a supply bottle and sucking the injection fluid into the syringe before injecting it into the one being treated. Such an arrangement is shown in U.S. Pat. Nos. 2,193,322; 2,244,969; 2,705,956; and 3,583,399.
Combinations of these two features in a syringe have appeared in U.S. Pat. Nos. 4,808,169 and 4,834,717. There are, however, some complexities of these patented syringes that have been avoided in the present invention.
It is an object of the present invention to provide an improved medical syringe assembly that includes a cartridge of injectable fluid and a safety needle cover. It is another object of the present invention to provide an improved syringe assembly with a built-in cartridge of injection fluid and a sheathed needle which can be protracted for use and retracted for disposal with virtually no danger of injury to the user. Still other objects will become apparent from the more detailed description which follows.